586 CYCADOPHYTAJSr FRONDS [CH. 



agrees very closely with Pterophyllum Carterianum Old. and 

 Morr.i from India. A comparison of the Eajmahal specimen 

 with Halle's figure leads me to regard the two fronds as probably 

 identical; The veins in the Indian species, which should also 

 be referred to Pseudoctenis, are prominent and from -5 to 1 mm. 

 apart ; the base of the lamina is slightly broadened and the veins 

 curve downwards towards the rachis in the lower decurrent 

 portion. The other Indian type, Pterophyllum Morrisianum^, 

 with which Halle compares his species is, howeverj not a Pseudo- 

 ctenis but should be included in Nilssonia and is probably identical 

 with Pterophyllum princeps Old. and Morr. 



Pseudoctenis Lanei Thomas. 



This species*, recently described from Middle Jurassic beds 

 at Marske, Yorkshire, has narrower linear lanceolate pinnae. 

 The Knear pinnae reach a length of 10 cm. and a breadth of 9 mm. 

 The veins are numerous, 10 in a breadth of 6 mm., and only one 

 cross-vein was noticed. In the decurrent lower edge of the 

 laminae the fronds are identical with Ctenis sulcicaulis. A very 

 good example of this species* in the York Museum is reproduced 

 by Mr Thomas in his account of Cleveland Jurassic plants. 



Pseudoctenis Balli (Feistmantel). 



A species described originally by Feistmantel^ as Anomozamites 

 Balli from the Barakar group of the Damuda series and afterwards 

 transferred to the genus Platypterygium, characterised by broadly 

 linear segments of imequal breadth attached obliquely or at 

 right-angles to a slender rachis. The apices of the segments 

 though usually imperfect appear to be truncate; the bases of 

 the pinnae are decurrent by their lower edge. The veins are 

 approximately 3 per millimetre; they are generally forked at 

 the base and in one or two places show cross-connexions. In 

 the middle of the frond the narrow rachis is exposed but in the 

 apical region it is covered by the laminae. The occurrence of 

 two divergent pinnae at the apex of the frond is a feature met 



1 Oldham and Morris (63) PI. xv. fig. 4. 



2 Ibid. PI. XV. fig. I. ; Feistmantel (77) PI. XLlii. fig. 1. 



' Thomas (LS^) p. 242, Pis. xxiv., xxvi. * Ibid. PI. xxvi. 



° Feistmantel (86) PI. ii. A. figs. 4—8. 



